<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			//1.数值型 number
			console.log(100)  //十进制整数
			console.log(0xff)  //十六进制整数
			console.log(077)  //八进制整数
			console.log(3.1415926)  //传统计数法
			console.log(3.5e3)  //科学计数法
			
			console.log(typeof 100)  //typeof 查看数据类型
			console.log(typeof 3.145)
			
			console.log(1/0)  //Infinity
			console.log(0/0)  //NaN
			
			//2.字符串类型 string
			console.log("Hello world!")
			console.log('Hello world!')
			console.log("Hello world,'js'!")
			console.log('Hello world,"js"!')
			console.log("Hello world,\"js\"!")
			console.log(typeof "hello")
			
			//转义字符
			//回车符\r
			//制表符\t
			
			//3.布尔型
			var a =10
			console.log(true)
			console.log(false)
			var a = 10;
			var b = 20;
			console.log(a==b)
			
			console.log(typeof (a==b))
			
			//4.特殊类型
			//未定义
			
			var c;
			console.log(c);         //undefined
			console.log(typeof c)   //undefined
			
			//
			var d = document.getElementById("div01")
			console.log(d)         //null
			console.log(typeof d)  //object
				
			</object>
		</script>
	</body>
</html>
